My opinions on a few things
Search! - I assume the update will take care of this problem.
Nested forums - Again I hope the new version of whatever software will take care of this. Then you could have one forum called "engines" with duratec and zetec related forums under those. Could also nest a few of the branches to keep the top level of forums a little cleaner.
Classifieds Forum - You need a few people to stay on top of this one and make sure you setup rules in advance. One forum I am on had so many problem with people selling things they did not have and scamming members that the rules for the classified section include that you must put up a picture of the parts you are selling with a sign with the date and your forum name written on it (no photshopping it in)
A different type of archive - Currently the "archive" has random conversations from 3.5 years ago and hidden in there you will find a few good threads. Make the archive all the good threads and split it out something like this.
General
Modifications
AutoX/Track
Mechanical
Detailing
Electronics/Stereo
Just get rid of the old stuff all the useful information has been moved into the new forum move threads here if they need to be kept around for later people to read.
Avatars - Don't care much for them. It might be nice to be able to give them to moderators if the software supports them but if you give everybody access to them you get people pushing the envelope of SFW in any way they can and going way over it many times.
Signatures - Continue blocking pictures from sigs they are annoying.
Attachments - Let people do small attachments limit size of attachment and how much one user can store.
HOW TO - Get a how to forum and put them all in there if the main site is not going to be updated maybe Lance could start pointing links from the main site into the forums so the information could be kept up to date without his need to give up control of the main site.
"Politics and Religion" - If you do this warn that you could be offended if you go here (yada yada yada) and to keep everything to that forum. Anything remotely dealing with Politics and Religion goes into there and anything said outside of that forum about it will be dealt with harshly.
Moderators - Yes it looks like a few more could be used in various places. Somebody named GTO Pete seems to be spreading himself a little thin and could use some help. I think most forums could use more than one moderator and I am not sure how many supermoderators/admins we have that can deal with all forums.
Remove some moderators ? - I saw that horseydug is still a moderator of Troubleshooting his last post was on 09/17/04 I don't know if he is still around or if his name is just sitting there.
SCCA/NASA Events - Rename this forum to something that is better understood as what it is for something like "Racing/ Motorsports" or "AutoX/Track" I would suggest moving drag racing into that forum and giving dyno their own seperate forum.
Main site - Either let somebody else update it or just point the link to the correct places in the forum so the information can be kept up to date. (or dare I suggest a Wiki for the FAQ and other things that should be updated)
